1. Field of the Invention
The present invention relates to the field of telecommunications. More particularly, the present invention relates to dimensioning wireless packet-based telecommunications systems, by determining the number of users or the number of base station channels relating to a target traffic throughput.
2. Acronyms
The written description provided herein contains acronyms which refer to various telecommunications services, components and techniques, as well as features relating to the present invention. Although some of these acronyms are known, use of these acronyms is not strictly standardized in the art. For purposes of the written description, the acronyms are defined as follows:                Code Division Multiple Access (CDMA)        Coding Scheme (CS)        Digital Control Channel (DCH)        Digital Subscriber Line (DSL)        Enhanced Data for Global Evolution (EDGE)        General Packet Radio Service (GPRS)        Global System for Mobile Communications (GSM)        Grade of Service (GoS)        International Telecommunications Union (ITU)        Packet Data Channel (PDCH)        Personal Digital Assistant (PDA)        Public Switched Telephone Network (PSTN)        Quality of Service (QoS)        Time Division Multiple Access (TDMA)        Traffic Channel (TCH)        Transmission Control Protocol/Internet Protocol (TCP/IP)        User Datagram Protocol/Internet Protocol (UDP/IP)        Wideband Code Division Multiple Access (WCDMA)        
3. Background Information
The communications industry has experienced significant growth in the demand for wireless communications. The increased demand is related, in part, to the improved quality and reliability of wireless networks, including mobile cellular networks, which have essentially evolved through three generations. The first generation included analog systems that modulated voice signals onto radio frequency (RF) carrier waves, which were transmitted and received between base stations and mobile units. The second generation of cellular networks introduced digital encoding of analog voice signals, and included the time division multiple access (TDMA) and code division multiple access (CDMA) cellular systems. The second generation required a symmetric, full-duplex network and was directed to accommodation of voice traffic. The third generation of cellular systems includes packet-switched transmissions and can accommodate voice, data, audio and video communications.
Third generation cellular networks can be integrated with other packet-based data networks, such as Internet Protocol (IP) based networks. Unlike the previous generation cellular systems, the connections are not dependent on circuit availability. The packet-switched capability enables virtual connections to any end point in the network. Also, new services may be provided, including always-on Internet access and multi-media applications.
Various protocols support packet-based communications in wireless networks, including General Packet Radio Service (GPRS), Enhanced Data for Global Evolution (EDGE) and Wideband Code Division Multiple Access (WCDMA). GPRS and EDGE are derived Global System for Mobile Communications (GSM) technologies, for sending and receiving data packets over a digital cellular network. GPRS, in particular, is well suited for sending and receiving small bursts of data. EDGE increases the data rate to about three times that of GPRS. WCDMA is designed to achieve multiple access by spreading the signal with different codes over a wideband (e.g., 5 MHz), and has been adopted as a standard by the International Telecommunications Union (ITU).
Like any telecommunications network, a packet-switched wireless network must be properly dimensioned. The network must be large enough to accommodate the users at an acceptable quality of service (QoS) for the large variety of supportable applications. However, the network must not be over provisioned, such that the network provider is not able to recover the capital investment in network resources, including base stations, antennae, back haul facilities and the like. Although dimensioning techniques are well established in circuit switched networks, such as the conventional public switched telephone network (PSTN), such dimensioning techniques are not generally and directly applicable to the packet-based networks.
For example, well established Erlang dimensioning models have been used extensively in conventional voice applications to predict the number of trunks needed to satisfy the load from users within a desired performance criteria, including an acceptable blocking probability indicated by the grade of service (GoS). Erlang dimensioning models, as well as other conventional network dimensioning techniques, include embedded assumptions based on well known statistical models of traffic arrival rates, such as the well known Poisson and Markov processes. Such traffic models generally capture the statistical characteristics of actual traffic reasonably well.
No comparable dimensioning tools are available to packet-based network planners, including third generation wireless cellular network planners. The current wireless packet-based network dimensioning tools are largely based on simulations of traffic through base station channels, and other system parameters, and are generally time consuming and have limited applications.
The present invention overcomes the problems associated with the prior art, as described below.